Field of Disclosure
The present disclosure relates to an improved method of and apparatus for reading bar code symbols in diverse scanning environments using laser scanning beam technology.
Brief Overview of the State of the Art
It is well known that the depth of field (DOF) of a laser scanning system is limited by the bandwidth and amplitude of the electrical scan data signal generated while scanning a laser beam across a code symbol located at a distance from the scanning.
For example, in a fixed scan speed/sweep scanning system, if the laser beam scans an object located a long distance from the scanning system, then the velocity of the laser beam across the object will be very high. Consequently, the signal amplitude received at the scanning system will be relative weak (because of the long distance traveled), and the signal frequency bandwidth will be very high due to the high velocity of the laser beam across the code structure.
Also, in a fixed scan speed/sweep scanning system, if the laser beam scans an object located a short distance from the scanning system, then the velocity of the laser beam across the object will be lower than when scanning long distance objects. Consequently, the signal amplitude received at the scanning system will be relative strong (because of the short distance traveled), and the signal frequency bandwidth will be relatively lower due to the low velocity of the laser beam across the code structure.
Such laser scanning performance characteristics of conventional fixed scanning systems create additional signal processing bandwidth requirements within the analog signal processing stage of conventional laser scanning systems. In turn, this complicates the design and increases the cost of such conventional laser scanning systems.
There is a great need in the art to provide a novel laser scanning code symbol reading system and method supporting an improved level control over the length of laser scan lines projected onto scanned objects, while maintaining the return signal bandwidth relatively constant during scanning operations, and avoiding the shortcomings and drawbacks of prior art methodologies and apparatus.